Two Flames, One Soul
by The Blue Twin
Summary: Prologue and chapter one go into more detail and explain where I plan to take this story c: Rin Okumura x OC
1. Prologue

Prologue

_Prologue_

_ There was once a time when demons and humans got along. They lived in the peaceful world of Assiah together. They became friends, brothers, sisters, wives, husbands, and even co-workers. But of course, this wouldn't be much of a story if everything went smoothly._

_ After hundreds of years of peace, hatred became to grow among a small group of humans. They thought that humans were too different from demons and that this would drive the demons to eradicate the human race. Little by little, fear grew in the hearts of these humans, and the good relationships that once were shared ceased to exist._

_ This group of humans later turned into what we now know as exorcists. They lived to drive out demons and even kill them. Eventually, the King of Demons decided to create a new world were the demons could live peacefully and safe from harm, and this land became known as Gehenna. However, he left it so that commuting between the two worlds would be easy for another demon._

_ Years passed, and no matter how much they hoped, demons were still feared and hated among what used to be their own friends and family. It even became so that hatred for the humans grew in the souls of the demons too. It was now a silent war between the two species, each one waiting for the perfect moment to destroy the other. However, there were those that still co-habituated with the humans and even fell in love with them, which was strictly prohibited. The children became what were known as "half-breeds". Many lived quiet lives, ignorant of their true origins and some actually knew of their being and either chose a life among humans, or sought refuge among the fellow demons in Gehenna._

_ Now, to more present times. The King of Demons, otherwise known as "Satan" among the humans, actually fell in love with one and had two sons born, only one of which inherited his dangerous and powerful blue flame. The other was left to be a human for he was too weak to accept such a powerful gift. An ex-exorcist and priest took them into his care, and hid their past from everyone, as that was their mother's dying wish._

_ On that same day, another child was born. She was also a half-breed, but her parents were different. Her father was a human and her mother was a demon. Her mother's name was Sakura and she was the second most powerful demon in recorded history and wielded the mysterious purple flame. She was a more peaceful spirit and lived peacefully among most humans._

_ Now, you may be asking yourself, "What does any of this have to do with anything?" Well, let's put it this way. Though the two souls come from vastly different origins and backgrounds, their similarities of who they are will drive them closely together. And them coming together may lead the way to peace between the humans and demons once more._


	2. Chapter 1

Chapter One: My Purple Flame

Ever since I was a young girl, I knew that I was different than most kids my age. It wasn't because I was intellectually ahead than all of them, though it was a little odd. No, it was because I am a half-demon. I didn't understand it then, but now it explained why my temper flared so quickly, why I was so incredibly strong and fast and why people always seemed to be so scared of me.

I remember the day my father finally explained who I really was and why I was this way. He sat me down on the bench outside the monastery which we lived in and told me about my mother, who I was never able to meet. Up until that point, by which I was about six or seven, I thought she had simply died. But that day, my father explained to me that she was a demon from the world of Gehenna and that she was very powerful and so was I. He told me that my gifts were nothing to be ashamed of but that people couldn't know about it because they wouldn't understand. It was that day that I began my training.

Shortly after our talk, I transferred out of school and was home-schooled by my father. He taught me much more than any school could. He was once an exorcist, before he met my mom and was on his way to becoming a Paladin, but once he met her, he realized that wasn't what he wanted to do. So he left and built a small monastery that also ran as an orphanage and that's where we lived. He also taught me many forms of combat, so if I ever needed to, I could protect myself.

But then, the year I turned thirteen, my father died.

I remember it was a rainy afternoon, and my father and I were sitting in his office reading books and drinking tea when there was a sudden knock at the door. We usually never received visitors unless it was for shipments from the town or another lost child. This time though, it was a group of exorcists.

*Flashback*

_"Father? Who is it?" I asked, my pale lavender eyes wide. My father's usually bright, cheery face went pale and stricken._

_ "Yuki, I need you to listen and quickly act. Go to your room and get your sword. If needed, protect yourself as best you can but don't leave your room under any circumstances, understand?"_

_ I nodded my head and did as I was told. As I ran to my room, I glimpsed outside through one of the large windows and saw three tall men cloaked in black. They held swords and guns and all kinds of weapons. That was the first day I began to feel afraid. I raced to my room and unsheathed my sword which was right beside my bed. My father had given it to me when I was ten to simply use in only dire emergencies._

_ I could hear banging on the front door and the shuffle of tiny feet as my father forced the children that we took care of into the emergency cellar. It was hidden behind a secret door in the living room so they would be safe._

_ Then I heard a crash as our front door was kicked open. My blood ran cold as ice and I stayed right where I was, trusting my father to be rid of these men fast. I could hear yelling, mostly of the other men. Slowly, I made my way to my door, which was creaked open and peered out, where I had a perfect view of what was happening._

_ My father had his sword out and pointed at the men who seemed to have him cornered. I swallowed a huge lump in my throat and I couldn't seem to shake this immense sense of dread._

_ "Yotsuda Crosswire, we are under direct orders from the High Council to bestow punishment upon you for your crimes. You have been charged guilty of not only laying with the demon, Sakura, but for also raising the bastard child that you two have created. By doing so, you have sealed your own fate. The punishment, is death." With that, I saw all three men raise their guns…and fire._

_ My father was fast and skilled, but he was no match for the speed of the bullets and the sheer amount of them. I had to watch, horrified as my father was shot countless times and died instantly. There wasn't a single thing I could do. I had to watch him die. As his body plunked to the floor, that's when I first experienced my true nature of being a demon._

_ I remember my vision turning red as my body grew warm with the flames that were licking my body, but not burning. My tail swung about and my canines grew to fangs and my eyes narrowed. I swiftly killed two of the men before they even had the chance to remember I was there. I remember clearly holding the last man by the throat and hissing at him._

_ "You bastards! That was my father!" I blinked back tears as my flames died out and I was more consumed by grief than anger. I still held the man as I whispered with a vicious tone, "Send this warning to your High Council. If another one you damned exorcists EVER sets foot on this property ever again, I will not only kill every single one of you that is on the property, but also the High Council themselves. And that is a promise." I set the man free and watched as he ran away, no doubt to tell the High Council was had occurred. _

_ I shortly afterwards disposed of the men's bodies and buried my father by the Sakura tree in the front of our house, and cleaned up the mess. Then I released the children and staff, telling them that everything was safe and okay now. When they asked about my father, I said he had died a noble death protecting us all, and later told the truth to the staff. We held a small vigil for him and placed a small stone over where he was buried with his name and birthday on it._

_ Weeks passed and no one showed up. Life soon returned to normal, or at least as normal as possible. But I never forgot what they did._

*Present time*

I shook myself out of my flashback and stared at the small stone. I had just turned sixteen this past week and things seemed to be better. The monastery was all mine by my birthright and I was at peace. I took care of the orphans, teaching them and caring for them. Some had even managed to find good homes. I still kept up with my studies, though I was already farther ahead than most college students. I also trained daily, prepared for anything.

"Yuki? It's getting cold, let's go inside!" I turned to face a small boy with creamy skin and freckles with wild and unruly brown hair and chocolaty brown eyes. Michael had been in our care since he was born and he was like a brother to me. He was about five now and when I turned eighteen, I planned on adopting him. He made my darkest days bright and always managed to put a smile on my face.

"Okay." He held out his hand and I took it. Things seemed to be happy and okay, though I knew really that was far from the truth. My heart still burned with a hatred for what the exorcists had done to my father. Killing him in cold blood just like that. And even though the rational part of me screamed for me to just let it be, I still really wanted revenge.

Oh what to do, what to do.


	3. Author's Note

Hey guys! I forgot to mention this at the beginning of my story but I kind of wanted to explain everything.

This is a Rin x OC story, though an actual romance or anything related probably won't happen for awhile, but don't get your hopes up! I plan to do something pretty complicated that I've never done before so bear with me!  
Also, I am aware that my format has been acting slightly off, and as long as it is brought to my attention I will fix it immediately c:


	4. Chapter 2

Chapter Two

It was another typical day at the monastery filled with my usual duties of making sure everything was going according to schedule. The morning was filled with taking care of a sick child, finding another a home and paying the bills. Now I was sitting in my father's office, reading through some papers and updating the children's profiles.

Just then, a knock came to my door. "Miss Crosswire? A letter came in the mail for you and its labeled urgent." One of the caretakers, Julie, came into the room then with a thick manila envelope, elegant writing printed on the front.

"Put it on my desk for now. I'll read it when I finish these papers." She did as she was told and left the room.

It seems strange to most people that I'm only 16 and already operating the monastery. Many have complained over the years, calling it illegal. But the bills were under my father's dear friends name, someone with the last name Pheles. And the contracts had his signature so it wasn't as if I was doing anything bad. More like the business was under someone else's name and I was just managing it and occasionally taking care of some of the finances.

A few minutes later I finished my paperwork for the day and glanced at the envelope. The writing was in cursive and hard to read, but it was clearly meant for me. I ripped it open and many papers came tumbling out. It included a brochure for True Cross Academy, registration papers, a hand written letter and a booklet on the dress code, rules and classes the Academy provided.

This wasn't the first time I had gotten letters from the Academy. It was the best school in the country and it produced some of the most famous people in the world. They only accepted the best of the best, with only the occasional bigot sneaking through the system. Though home-schooled, I was already at a masters degree level of schooling. I still hadn't completed some college courses that would allow me to graduate but with my abilities it wouldn't take me very long to do so. My father taught me that the only way to get ahead in life was to work hard everyday and not take a single thing for granted. I never attended regular school since the day my father told me about who I am. I studied and trained at home 24/7.

Another thing about True Cross Academy: they trained exorcists in their cram schools and the High Council that sentenced my father to death resided there. Going to receive an education there would basically be saying that there was free range to kill me if they wanted to.

I shook my head, about to recycle these papers once more when the hand written letter caught my eye again. The envelope did say it was urgent. Maybe the High Council was about to make its next move?

I grabbed the paper and began reading, my heart pounding.

_Dear Miss Yuki Crosswire,_

_You do not know me, as your father never had the opportunity to introduce us before his untimely death. But I'm sure you've heard my name before. After all, I am the co-signer on your monastery's contracts and the person who has his name written on the bills._

_Anyways, I felt as though now was the correct time to contact you. You are now old enough and smart enough to truly understand the vicious world we live in today. Especially under our similar circumstances._

_I've decided to extend an invitation to join True Cross Academy to not only further your education, but because I would like to help you._

_I can assure you that any doubts you may have about attending the Academy can be wiped away. I've made sure the High Council can't do anything and reminded them on what people like you are capable of._

_Once you complete your registration form and send it to my personal address which is on the envelope I've mailed this to you on, we can talk more on the matter._

_I wish you and the children and the staff well._

_~ Headmaster of True Cross Academy Mephisto Pheles~_

I shook my head and re-read the letter three times. Pheles? So the headmaster of an exorcist training school has not only helped me keep the monastery, but was close friend with my father whom the exorcists considered a traitor? And he wanted me to attend the same school as those that killed my kind and killed my father?

I should've just torn up the papers and threw them away like I always did. But there was something about the words he spoke that wanted me to hear what he had to say. Maybe he knew something that could help me get revenge for my father or even at least clear his name for good.

Doesn't matter my excuse for doing so, but after reading that letter a few times and thinking about it for ten minutes, I found myself filling out and completing the registration papers for True Cross Academy.


	5. Chapter 3

One week after signing away the papers that would officially make me a student at True Cross Academy, I received a phone call from an all too peppy receptionist saying that someone would be arriving within the next few days to collect my things and take me to the Academy.

I also received only a few days beforehand, my schedule and two sets of each uniform. One set was meant obviously for the summer and spring time. It consisted of a short sleeved school girl shirt in white and the standard black skirt. There was a list that came with it of appropriate accessories and what was and wasn't allowed. The next set of clothes were white button ups- long sleeved- and black pants with the standard jacket. I remember reading somewhere that only the boys could wear pants, but I supposed they had gotten my small letter detailing I was more comfortable in pants.

The day I was supposed to be picked up, my suitcases were neatly stacked outside and I was wearing one of the uniforms. It was an especially warm day so I chose the skirt ensemble. Despite the fact that I would be around the very kinds of people I couldn't stand, I refused to look anything less than polished.

I sat with Micheal in my room, which he had decided to make his own until I came back. He was terribly heartbroken over the fact that I was leaving. He didn't understand, he was far too young to. I wished I could tell him why I was doing all this, but I didn't even understand why myself. The only thing I knew was that this Mephisto knew my father and he knows about me, and what happened. And I needed to know everything I could.

"Do you really have to go?" He looked at me with his big eyes, full of sadness. I smiled sadly and pushed his hair away from his face, hugging him.

"I'm afraid so. I promise I'll tell you more when I can, just know that I will come and visit whenever I can. And I'll call all the time." He seemed to cheer up a little at that.

"Ms. Crosswire, there's a limo waiting outside for you. The men have already taken your bags." I glanced at my clock. Noon exactly. Punctual. At least I could give the Academy that. I gave Micheal one last hug and kiss on the head.

"I love you Micheal. Don't forget that. I'll be back before you know it." I smiled widely. He smiled back, hugging me with all his might. He was trying so hard not to cry in front of me, so I got up and started walking.

The outside air was warm, but not unpleasantly. My long, black hair was down in gentle waves and my pale violet eyes scanned the limo. It was a standard black, but looked relatively new. As I got closer, a man stepped out from the limo. He was just a bodyguard of some kind sent from the school it seemed with his simple black suit. He opened the limo door for me, which I slipped in, taking one glance at the monastery. My home. My home that I was leaving for the first time. I felt a pang of homesickness, even though the car hadn't even begun moving again.

"I imagine this will be quite an experience for you." I jumped, not expecting someone else to be in the car. I turned to face an older man with purple hair and…..well, it can only be described as an extremely flamboyant outfit. Certainly unlike anything I had ever seen before. I could only stare.

He chuckled a bit. "My apologies ma'am. I didn't mean to startle you. The name is Mephisto Pheles, but at True Cross Academy I am just known as Headmaster Pheles." He tipped his fancy white hat at me in a polite manner, his entire demeanor relaxed and calm, like he was talking to an old friend.

"So, you're the one who sent me that letter." I stated, not as a question. He nodded his head. "I had meant to get into contact with you sooner, but my circumstances would not permit me to. You see, due to my…position, I'm kept under close watch by the High Council. If they had known I was trying to contact you, I would have been killed and the monastery would've gone to shambles."

"But don't they know you're the secondary signer? And now don't they know I'm going to the Academy?" I crossed my arms as we drove away, momentarily forgetting my homesickness.

"No. I made sure that all my legal issues and what I do outside of work stays outside of work. There are many human laws that protect me." I raised an eyebrow. Human laws? Was he…? Before I could ask he continued on. "The only thing the High Council knows is of your acceptance. They'll be trying to keep close tabs, but there isn't much they can do in a school environment without drawing attention. As far as everyone in that school goes, they think you're a human and it would look awful on them to try and peg you as a half-breed, especially since they don't have proof. So, you my dear, are in the clear." He explained all this with ease, as if it were as simple as the alphabet. Which, it actually was. I grinned a little at the thought of the High Council not being able to do anything but watch as one of their own enemies attended one of their facilities.

"You mentioned before that there are many human laws that protect you. Are you insinuating that you are not a human yourself?" He raised his eyebrows, a little surprised that I caught onto that.

"My, you are good at catching the little details. No, my dear, I am not a human. I am a demon, straight from Gehenna." He smiled at me. "I know, it seems strange that the High Council is allowing the very thing they hate the most work for them. Those details aren't important to you, trust me. Just know that I am a man who knows many secrets. Secrets that they wouldn't want to get out and make them look bad, especially concerning issues like your father."

This peaked my interest any further. But before I could ask more questions, we made another stop. Mephisto held up a finger. "I know you have a lot of questions, and I will provide the answers, but first we need to pick someone up. Fair warning, he runs on a short temper and can be a complete idiot." Mephisto leaned in closer, whispering. "But I think you two will get along just fine. You may even find that you two share a lot in common."

With that, he left the car, leaving me stunned. What was he going on about? Who were we picking up? I found myself with more questions than answers. Today was supposed to clear everything up for me and I just found myself even more confused.

A couple of minutes later, I could hear two male voices, one Mephisto's and one belonging to someone I didn't recognize. But he sounded about my age. It only took another minutes before they were both entering the car, Mephisto introducing us immediately.

"Yuki, this is Rin. Rin, this is Yuki. She will be entering the Academy as of today so be sure to treat her well." He made a stern face at the young man. I turned to greet him, being nothing but polite.

I could tell Rin trained a lot, he had the lean body and muscles of someone who trained everyday. No doubt he was probably an exorcist in training. He had a messy mop of dark hair and the most stunning eyes I had ever seen. Unlike mine, they were a deep blue. He had strong features, but right now he just had a goofy smile on his face, which looked sort of adorable.

"Nice to meet ya." He stated, holding out his hand. I took it in my own, gently shaking it and smiling.

"Nice to meet you as well." Mephisto clapped his hands, clearly happy. "Wonderful, wonderful. Now, its great that I have you both here. I actually never expected this to happen!"

We both raised our eyebrows. "What are you talking about Mephisto?" Rin asked, confused.

Mephisto only laughed. "Well, do pardon me for just throwing this out there. But I never expected to have the son of Satan and the daughter of Sakura to be going to an exorcist training school and riding in the same limo as me!" He laughed, while I sat there stunned once more.

Son of Satan? I turned my head to look at Rin, who was giving me the same once over.

Clearly, I had more to worry about than the High Council.


	6. Chapter 4

The rest of the car ride was quiet and quite frankly, awkward. Rin and I didn't speak not once after that, averting our gazes elsewhere. My eyes went to the window, watching the scenery pass and keeping my attentions away from the two other people in the limo. Mephisto may have been excited by our presence, but I didn't have the time nor energy to bother. After all, what were the Son of Satan and the Daughter of Sakura supposed to say to one another? Nice to meet you?

It wasn't like I was going to this school anyways to make friends and see other demons. I had a clear mission in mind: get revenge for my father and make sure True Cross Academy never came near me again.

Mephisto pulled out his phone shortly after the awkwardness settled, someone clearly trying to get his attention. He spoke in a low voice, so neither of us could hear the conversation taking place. Most likely it was the High Council making sure I was indeed coming to the Academy and I was who I said I was. I smiled thinking about them all scared, cringing in their seat as they read my qualifications and transcripts.

"Yes, don't worry we will be there shortly. I just had to stop and pick up something else on the way...Alright bye." He hung up the phone right as we pulled into some kind of parking area. I looked out my window to see True Cross Academy in all of its glory. It stood tall and proud as it always had, with large clusters of building surrounding it. No one was wandering around outside, which was a good thing considering I didn't want people staring at me...yet.

"Listen here you two..." I turned my head towards Mephisto, who had a very serious look on his face. Rin was paying attention too, leaning in a bit. Mephisto continued. "No one knows your identities. Rin, you know this already but I have to make it as clear as I can. Rin has the cover of being an exorcist, he's training right here on these grounds, so he has good cover. Not to mention his brother is a human so that makes it better." Brother? My eyes widened at the thought of two sons of Satan. Hopefully they wouldn't be a problem. "Now, look Yuki, I don't want you to do anything that you don't want to but I'm afraid certain measures have to be taken to ensure your identity and protection. We had to place you in the exorcist classes, just for appearances."

I instantly recoiled. "You can't do that! It completely goes against everything I stand for. I refuse to cause any more harm than these exorcists have done." I spat, crossing my arms. Rin looked over at me, surprise written all over his face. I just glared ahead, addressing him. "What? You'd be surprised not every half-breed and human out there wants to join in and kill a bunch of demons, most of them harmless."

"Harmless? You clearly don't know what you're talking about. Tch." Rin scoffed back. I sat up, getting ready to shoot some smart comments but Mephisto interrupted before the conversation took a deadly turn. "Now now you two. I know you both have different views on the situation but that's not important. You just have to make sure your true identities don't come out and get yourselves killed. Now Yuki, its not ideal but I've arranged it so you can back out of whatever physical training you want to. Most of the classes don't even require going out and dealing with actual demons, just the basic book stuff, which you know. Perfect cover. Just put up with it until all that's done is done alright?" He gave me a look, clearly trying to hide my agenda from Rin, who looked very curious.

I sighed. There was no point in fighting it. I couldn't bring attention to myself this early in the game. "Fine. But just so you know, I will make sure o finish this all up quickly so I can go home as soon as possible." Mephisto nodded in understanding.

"Of course. I didn't expect anything less. You are your father's daughter." I smiled at that.

"Now come on you two, we have to get you to your dorms and I have to get Yuki set up." With that, we exited the limo just as the bell rang. Great.

Rin wen ahead of us, even though we were going in the same direction. I nodded in his path. "What's his problem?"

Mephisto sighed. "Rin is a hot head, especially on matters he's passionate about. Being an exorcist is one of them. You see, before he knew he was the son of Satan, he had a hard time fitting in. He was so angry all the time, getting into fights and just plain violent. He lived with a monk of sorts who ran a monastery similar to your own, and he was friends with Rin's mother before she passed on. Anyways, he raised them like his own. They had their good and bad times but always came back together in the end." He smiled a bit as we passed a group of students. They stared and whispered among themselves. I ignored them, listening to Mephisto instead.

"What happened?" I asked gently. He frowned.

"One day Rin started seeing them, the demons. Low class, relatively harmless. That is, until a higher class took the body of a human and attempted to bring him back to Gehenna, even though Rin's demon form was still sealed away at the time. He managed to escape, breaking through some of the seals and returning to the monastery. There, his father tried to protect him but Satan was able to detect his aura and tracked him down. During a moment of weakness, his father let his guard down and Satan was able to possess him."

"That's impossible. Any host would give out before he could even open his mouth." I replied, not believing him for a moment.

"Well, Rin's father wasn't just another monk. He was Paladin of True Cross Academy, Shiro Fujimoto." My eyes widened.

"He's the one that took my father's place after he died." I whispered. Mephisto nodded, continuing his story.

"That he did. Anyways, he was able to possess him for a short amount of time and opening up the Gate, trying to take Rin with him. But Rin decided to save him and his father buy releasing the seal on his sword he always carries around, revealing his demon form. Sadly it was too late by the time he closed the Gate, as when Satan left Shiro's body, he killed him. And so, Rin vowed to kill Satan as vengeance."

I was in shock. The fact that our stories were more similar than I first imagined was beyond me. "That's...interesting actually. I never expected to meet someone with the same ambition as I. But we are clearly playing for two different sides so to speak."

Mephisto nodded. "Yes. Rin won't like nor understand that. But what's important to know is that he will try to stop you if he feels as though you're jeopardizing him, his mission, his brother or any of his friends. Basically, he will try to stop you if he finds out what you're up to."

I waved him off. "He won't trust me. Sure he knows I'm not all up for killing demons and he's probably curious as to why I'm here, but he'll never catch on. All my investigating will take place right under their noses, they won't even know what hit them." I smiled.

"You are certainly going to make this place a lot more entertaining aren't you?"

I laughed. "I can definitely try Mephisto, I can try."

**Okay, sorry for the long wait! I just graduated high school and have been dedicating most of my time to that right now. But since it's summer I will try to update more often and get this story rolling. Next chapter should start some good stuff, even a fighting scene!

Also, I have a Quotev account, with a couple other fanfictions on there if you want to check them out! My account is Yourstrulymariah I believe. I'm constantly updating on there since the format is easy and simple.

Also, comment below what you think and where you would like to see the story go! Even ideas for future chapters. This is as much your story as it is mine, after all, you guys have to read it!

Thank you so much for reading and sticking around! Love you guys! 3**


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